1. Field of the Invention
This invention relates to improved anchors and reinforcements for masonry backup walls that serve cavity wall constructs with larger-than-normal cavities between the masonry backup wall and the facing brick veneer. More particularly, the invention relates to cavity walls requiring novel anchoring systems for spanning such cavities and, further to the use of resistance-welded, wire formatives to meet existing wind shear and seismic specifications.
2. Description of the Prior Act
Recently, there have been significant shifts in public sector building specifications which have resulted in architects and architectural engineers requiring larger and larger cavities in the exterior cavity walls of public buildings. These requirements are imposed without corresponding decreases in wind shear and seismic resistance levels or increases in mortar bed joint height. Thus, wall anchors are needed to occupy the same xe2x85x9c-inch-high space in the inner wythe and tie down a veneer facing material of an outer wythe at a span of two or more times that which had previously been experienced.
Exemplary of the public sector building specification is that of the Energy Code Requirement, Boston, Mass. (see Chapter 13 of 780 CMR, Seventh Edition). This Code sets forth insulation R-values well in excess of prior editions and evokes an engineering response opting for thicker insulation and correspondingly larger cavities. Here, the emphasis is upon creating a building envelope that is designed and constructed with a continuous air barrier to control air leakage into or out of conditioned space adjacent the inner wythe.
Another application for high-span anchoring systems is in the evolving technology of self-cooling buildings. Here, the cavity wall serves additionally as a plenum for delivering air from one area to another. While this technology has not seen wide application in the United States, the ability to size cavities to match air moving requirements for naturally ventilated buildings enables the architectural engineer to now consider cavity walls when designing structures in this environmentally favorable form.
In the past, the use of wire formatives have been limited by the mortar layer thicknesses which, in turn are dictated either by the new building specifications or by pre-existing conditions, e.g. matching during renovations or additions the existing mortar layer thickness. While arguments have been made for increasing the number of the fine-wire anchors per unit area of the facing layer, architects and architectural engineers have favored wire formative anchors of sturdier wire. On the other hand, contractors find that heavy wire anchors, with diameters approaching the mortar layer height specification, frequently result in misalignment. Thus, these contractors look towards substituting thinner gage wire formatives which result in easier alignment of courses of block.
In the past, there have been investigations relating to the effects of various forces, particularly lateral forces, upon brick veneer construction having wire formative anchors embedded in the mortar joint of anchored veneer walls. The seismic aspect of these investigations were referenced in the first-named inventor""s prior patents, namely, U.S. Pat. Nos. 4,875,319 and 5,408,798. Besides earthquake protection, the failure of several high-rise buildings to withstand wind and other lateral forces has resulted in the incorporation of a requirement for continuous wire reinforcement in the Uniform Building Code provisions. The first-named inventor""s related SeismiclipR and DW-10-XR products (manufactured by Hohmann and Barnard, Inc., Hauppauge, N.Y. 11788) have become widely accepted in the industry. The use of a wire formative anchors and reinforcement wire structures in masonry walls has been shown to protective against problems arising from thermal expansion and contraction. Also, such structures have improved the uniformity of the distribution of lateral forces. However, these past investigations do not address the mortar layer thickness vs. the wire diameter of the wire formative or the technical problems arising therefrom.
Over time and as the industry matured, besides the Uniform Building Code other standards came into existence, including the promulgation by the ASTM Committee A01 on Steel of the Standard Specifications for Masonry Joint Reinforcement, A951-00 (hereinafter A951). The Standard sets forth that masonry joint reinforcement is to be assembled by automatic machines to assure accurate spacing and alignment of all members of the finished product and that longitudinal and cross wires are to be securely connected at every intersection by an electric-resistance welding process that includes fusion welding together with applied pressure to join the materials. The Standard further sets forth details as to the exterior of the longitudinal wires and the mechanical requirements of the overall construct.
According to the ASTM Committee A01, joint reinforcement has been used in the masonry industry since 1940. In introducing A951, the Committee states:
For most of the period since then, its manufacture has been limited to a relatively small group of producers and users who simply referred to xe2x80x9cmanufacturers"" recommendationsxe2x80x9d as the standard of quality and acceptance. With the adoption of a new consensus standard for the design of masonry, it became clear that a standard for the manufacture of joint reinforcement was needed. In developing this standard it was decided to use a format similar to that used for the ASTM Standard for Welded Wire Fabric, Plain, for Concrete Reinforcement, Specification A185, since many people had the notion that joint reinforcement was used in a manner similar to wire mesh. A significant difference between wire mesh and joint reinforcement arose when an attempt was made to fashion the requirements for weld shear strength after those in Specification A185.
The Committee found that almost all of the manufacturers of joint reinforcement use butt welds so that the total thickness of material at a weld is as small as possible. This is important since, in conventional mortar bed joints, there is not much room to install joint reinforcement. In addition, it found that in masonry joint reinforcement the majority of product produced is that with a xe2x80x9ctrussxe2x80x9d configuration in which the angle of intersection varies for each different width of product produced since the pitch between welds is a constant 16 inches. These characteristics differentiated the testing for weld shear strength from those of Specification A185 and resulted in the development of a distinct test methodology.
In the course of preparing this disclosure several patents became known to the inventors hereof. The following patents are believed to be relevant and are discussed further as to the significance thereof:
It is noted that with some exceptions these devices are generally descriptive of wire-to-wire anchors and wall ties and have various cooperative functional relationships with straight wire runs embedded in the inner and/or outer wythe.
U.S. Pat. No. 3,377,764xe2x80x94D. Storchxe2x80x94Issued Apr. 16, 1968
Discloses a bent wire, tie-type anchor for embedment in a facing exterior wythe engaging with a loop attached to a straight wire run in a backup interior wythe.
U.S. Pat. No. 4,021,990xe2x80x94B. J. Schwalbergxe2x80x94Issued May 10, 1977
Discloses a dry wall construction system for anchoring a facing veneer to wallboard/metal stud construction with a pronged sheetmetal anchor. Like Storch ""764, the wall tie is embedded in the exterior wythe and is not attached to a straight wire run.
U.S. Pat. No. 4,373,314xe2x80x94J. A. Allanxe2x80x94Issued Feb. 15, 1983
Discloses a vertical angle iron with one leg adapted for attachment to a stud; and the other having elongated slots to accommodate wall ties. Insulation is applied between projecting vertical legs of adjacent angle irons with slots being spaced away from the stud to avoid the insulation.
U.S. Pat. No. 4,473,984xe2x80x94Lopezxe2x80x94Issued Oct. 2, 1984
Discloses a curtain-wall masonry anchor system wherein a wall tie is attached to the inner wythe by a self-tapping screw to a metal stud and to the outer wythe by embedment in a corresponding bed joint. The stud is applied through a hole cut into the insulation.
U.S. Pat. No. 4,869,038xe2x80x94M. J. Catanixe2x80x94Issued Sep. 26, 1989
Discloses a veneer wall anchor system having in the interior wythe a truss-type anchor, similar to Hala et al. ""226, supra, but with horizontal sheetmetal extensions. The extensions are interlocked with bent wire pintle-type wall ties that are embedded within the exterior wythe.
U.S. Pat. No. 4,879,319xe2x80x94R. Hohmannxe2x80x94Issued Oct. 24, 1989
Discloses a seismic construction system for anchoring a facing veneer to wallboard/metal stud construction with a pronged sheet-metal anchor. Wall tie is distinguished over that of Schwalberg ""990 and is clipped onto a straight wire run.
U.S. Pat. No. 5,392,581xe2x80x94Hatzinikolas et al.xe2x80x94Issued Feb. 28, 1995
Discloses a cavity-wall anchor having a conventional tie wire for mounting in the brick veneer and an L-shaped sheetmetal bracket for mounting vertically between side-by-side blocks and horizontally on atop a course of blocks. The bracket has a slit which is vertically disposed and protrudes into the cavity. The slit provides for a vertically adjustable anchor.
U.S. Pat. No. 5,408,798xe2x80x94Hohmannxe2x80x94Issued Apr. 25, 1995
Discloses a seismic construction system for a cavity wall having a masonry anchor, a wall tie, and a facing anchor. Sealed eye wires extend into the cavity and wire wall ties are threaded therethrough with the open ends thereof embedded with a Hohmann ""319 (see supra) clip in the mortar layer of the brick veneer.
U.S. Pat. No. 5,456,052xe2x80x94Anderson et al.xe2x80x94Issued Oct. 10, 1995
Discloses a two-part masonry brick tie, the first part being designed to be installed in the inner wythe and then, later when the brick veneer is erected to be interconnected by the second part. Both parts are constructed from sheetmetal and are arranged on substantially the same horizontal plane.
U.S. Pat. No. 5,816,008xe2x80x94Hohmannxe2x80x94Issued Oct. 15, 1998
Discloses a brick veneer anchor primarily for use with a cavity wall with a drywall inner wythe. The device combines an L-shaped plate for mounting on the metal stud of the drywall and extending into the cavity with a T-head bent stay. After interengagement with the L-shaped plate the free end of the bent stay is embedded in the corresponding bed joint of the veneer.
U.S. Pat. No. 6,209,281xe2x80x94Ricexe2x80x94Issued Apr. 3, 2001
Discloses a masonry anchor having a conventional tie wire for mounting in the brick veneer and sheetmetal bracket for mounting on the metal-stud-supported drywall. The bracket has a slit which is vertically disposed when the bracket is mounted on the metal stud and, in application, protrudes through the drywall into the cavity. The slit provides for a vertically adjustable anchor.
U.S. Pat. No. 6,279,283xe2x80x94Hohmann et al.xe2x80x94Issued Aug. 28, 2001
Discloses a low-profile wall tie primarily for use in renovation construction where in order to match existing mortar height in the facing wythe a compressed wall tie is embedded in the bed joint of the brick veneer.
None of the above provide the high-span anchors and reinforcements for the masonry backup walls as applied to structures having larger-than-normal cavities. In the above-cited related Application, wire formatives are compressively reduced in height at the junctures between the wall reinforcements and the wall anchors. This enabled the stacked components to be inserted within the bed joints and still have a covering of mortar. While this approach worked well, alternatives utilizing electric resistance welding techniques are presented hereinbelow.
In general terms, the invention disclosed hereby includes a high-span anchor and reinforcement device for a cavity wall combined with an interlocking veneer tie. The wall construct has an inner wythe or backup wall and an outer wythe or facing wall. The wythes are in a spaced apart relationship and form a larger-than-normal cavity therebetween. In the embodiments disclosed, a unique combination of a wall anchor, a reinforcement and a veneer tie is provided. The invention contemplates that the primary components of the system are structured from reinforcing wire and wire formatives, such as truss reinforcement or ladder mesh reinforcements, and provide wire-to-wire connections therebetween. Further, the various embodiments combine wire formatives which are selectively and compressively reduced in height by the cold-working thereof.
The embodiments of the invention disclosed hereby include high-span anchors incorporating a low-profile veneer tie for use in the construction of a wall having an inner wythe with thick strips of insulation attached thereto. Because of compressive reduction in height of extended leg portions that span the insulation, the air leakage at and adjacent heavy wire components is substantially overcome. This results as the strips of insulation are installed so that the seams between the strips are coplanar with the inner wythe bed joints. The compressively reduced in height wall anchors protrude into the cavity through the seams, which seams seal thereabout so as to maintain the integrity of the insulation and minimize air leakage along the wall anchors. The invention contemplates that some components of the system are as described in U.S. Pat. Nos. 5,408,798; 5,454,200; and 6,279,283 and that the wire formatives hereof provide a positive interlocking connection therebetween specific for the requirements created by this high-span application.
In the mode of practicing the invention, wherein the inner wythe is constructed from a masonry block material, the masonry anchor has, for example, a truss portion with eye wire extensions welded thereto. The eye wires extend across the insulation into the cavity between the wythes. Each of the eye wires accommodates the threading thereinto of a wire facing anchor or wall tie with either a pintle inserted through the eye or the open end of the wall tie. The wall tie is then positioned so that the insertion end is embedded in the facing wall. The masonry anchor is embedded in a bed joint of the interior wythe. Wall and veneer ties compressively reduced in height are described as being mounted in bed joints of the inner and outer wythes. The close control of overall heights permits the mortar of the bed joints to flow over and about the wall reinforcement and wall tie combination inserted in the inner wythe and insertion end of the wall in the outer wythe. As the test data shown below confirms, the use of the specific wire formatives hereof, which employ extra strong material and benefit from the cold-working of the metal alloys, the high-span reinforcement and wall anchor devices meet the unusual requirements demanded.
It is an object of the present invention to provide, for cavity walls with a larger-than-normal cavities, anchoring systems and anchors for the masonry backup walls thereof and provide for the securement of facing veneers.
It is another object of the present invention to provide labor-saving, high-span anchoring systems which employ resistance welded, wire formatives in the mortar joint of the inner wythe and is adapted to be positively interconnected with a veneer tie inserted into the outer wythe.
It is yet another object of the present invention to provide a high-strength, anchoring systems for heavily insulated cavity wall structures which utilizes high cross-sectional area components for wall reinforcement of the inner wythe in a manner such that the mortar layer coverage thereof is maintainable.
It is a further object of the present invention to provide a high-span anchoring systems comprising a limited number of component parts that are economical of manufacture resulting in a low unit cost.
It is yet another object of the present invention to provide a high-span anchoring systems which are easy to install and which meet seismic and shear resistance requirements.
It is a feature of the present invention that the portion of the wall anchor embedded in the bed joint of the inner wythe is fused during resistance welding thereof to the wire reinforcement portion.
It is another feature of the present invention that the veneer anchor, the wall tie and the combined wall anchor and wall reinforcement are dimensioned so that, when inserted into the respective mortar layers, the mortar thereof can flow around the wall-tie-to-reinforcement-wire joint.
It is yet another feature of the present invention that the reinforcement wire of the inner wythe is combinable with a low-profile wall anchor to span the insulation of the cavity wall at the seam thereof and that the wall tie is sealingly surrounded by the insulation.